1. Field of the Invention
The present invention relates generally to a zoom lens device, and more particularly to a simple inexpensive zoom lens device that can perform a macro shooting. The present invention relates generally to a zoom lens device, and more particularly to an inexpensive zoom lens device that can easily perform a macro shooting with a small aperture.
2. Description of the Related Art
In a conventional zoom lens device, when a normal shooting mode for shooting a subject with a normal subject distance is switched to a macro shooting mode, a zoom lens moves forward beyond a telephoto end and a focus lens moves.
When an aperture of sectors is small, in order to make a field depth larger for a macro shooting, a lens device can be focused on a depth-of-field subject and a precise automatic focus is not needed. When the normal shooting mode is switched to the macro shooting mode, the conventional zoom lens device stops sectors while they are opening to obtain a small aperture.
However, since the zoom lens moves forward beyond the telephoto end, the zoom lens device is large. To address this problem, if the telephoto end is used only for the macro shooting, a telephoto end for the normal shooting is close to the wide-angle end, and thus the zooming ratio is low.
For a short-distance shooting, the number of automatic focus needs to be increased because of a small field depth. Thus, the stop position of the lens needs to be precisely controlled, and this makes the lens device more expensive. To increase the field depth, a programmed shutter can be used with a small aperture. In this case, sectors need to be precisely controlled, this makes the lens device more expensive. Also, the shutter speed becomes fast, and the background is underexposed even if the main subject is appropriately exposed with an electronic flash.
Since the conventional zoom lens device controls the sectors with pulses, the structure and control of the sectors are complicated, and this makes the zoom lens device more expensive.
It is therefore an object of the present invention to provide a simple inexpensive zoom lens device that can perform a macro shooting.
It is therefore an object of the present invention to provide an inexpensive zoom lens device that can easily perform a macro shooting with a small aperture.
The above object can be achieved by providing a zoom lens device wherein an aperture at a predetermined zooming step that is between a telephoto end and a wide-angle end is smaller than apertures at the other zooming steps.
The above object can be achieved by providing a zoom lens device, comprising: a zoom lens with a plurality of zooming steps; a choosing device that chooses a macro shooting mode for obtaining a close-up of a subject; a driving device that moves the zoom lens to a predetermined zooming step that is between a telephoto end and a wide-angle end when the choosing device chooses the macro shooting mode; and an aperture restricting device that changes apertures according to the zooming steps so that an aperture at a predetermined zooming step that is between a telephoto end and a wide-angle end is smaller than apertures at the other zooming steps.
According to the present invention, the aperture at the predetermined zooming step that is between the telephoto end and the wide-angle end is smaller than apertures at the other zooming steps, and the predetermined zooming step is used only when the macro shooting mode is chosen. In the present invention, the predetermined zooming step between the telephoto end and the wide-angle end is set only for the macro shooting mode, and the aperture in the macro shooting mode is small to make the field depth large. Therefore, the lens does not have to be precisely controlled, and the simple lens device can preform the macro shooting. In addition, the lens device can be focused on a depth-of-field subject, and the automatic focus does not need to be precisely preformed. Also, the appropriate exposure can be obtained even if an electronic flash fully emits a light, and the electronic flash light does not need to be adjusted. Moreover, since the telephoto end is not only set for the macro shooting, the zooming ratio is high in the normal shooting.
Furthermore, since the predetermined zooming step is close to the telephoto side in which the view angle changes more largely than in the wide-angle side, the user does not realize the change of the view angle at the time of the normal shooting.
The above object can be achieved by providing a zoom lens device, comprising: a zoom lens; sectors that work as a diaphragm; and an aperture switching device that switches an aperture of the sectors when the zoom lens is moved beyond one of a telephoto end and a wide-angle end.
According to the present invention, when the zoom lens is moved beyond the telephoto end or the wide-angle end, the aperture switching device switches the aperture to a small aperture. This makes the field depth larger, and the lens device can be focused on a depth-of-field subject. Thus, the macro shooting can be easily performed.
Specifically, the zoom lens device comprises the zoom lens: the sectors that work as the diaphragm; an aperture restricting device composed of a cam follower and a cam member with a first cam surface, a second cam surface and a third cam surface; a pushing device that pushes the cam follower against the first cam surface and the second cam surface; and the aperture switching device. The cam member has a first cam surface that restricts the aperture according to the focal length of the zoom lens, a second cam surface that faces the first cam surface and restricts the aperture to the small aperture, and a third cam surface that is formed out of a range between the telephoto end and the wide-angle end and that guides the cam follower from the first cam surface to the second cam surface. The aperture switching device moves the zoom lens beyond the telephoto end or the wide-angle end to move the cam follower from the first cam surface to the second cam surface through the third cam surface and change the pushing direction of the pushing device from the direction of the first cam surface to the direction of the second cam surface.
When the zoom lens is moved beyond the telephoto end or the wide-angle end, the pushing device pushes the cam follower against the second cam surface, and the aperture is smaller than the other apertures. The lens device can obtain the small aperture only by moving the zoom lens beyond the telephoto end or the wide-angle end. Since the known aperture restriction needs little change to realize the aperture restriction of the present invention, the number of parts is not increased, and the lens device is small and inexpensive.
Since the macro shooting is performed with the small aperture, the exposure is appropriate even if the electronic flash fully emits the light. Thus, the electronic flash does not need to be adjusted. If a toggle mechanism is used as the pushing device, the one toggle mechanism can change the pushing direction.
The cam member has a fourth cam surface that guides the cam follower from the second cam surface to the first cam surface when the zoom lens is returned to a collapsed position. For example, if the fourth cam surface corresponds to the collapsed position, the small aperture for the macro shooting can be obtained at the zooming steps from the telephoto end to the wide-angle end. When the cam follower is returned to the first cam surface, the pushing direction of the cam follower is changed from the direction of the second cam surface to the direction of the first cam surface. This switches the macro shooting mode to the normal shooting mode.